In this article, you will gain a deeper insight into the fascinating world of underglazes. Whether you’re an experienced artist or just starting out, understanding underglazes is crucial in creating vibrant and long-lasting ceramic artworks. We will explore the various uses and application techniques of underglazes, as well as their different effects on both greenware and bisqueware. By the end, you’ll be equipped with the knowledge to confidently experiment with underglazes and unlock endless creative possibilities. So, let’s embark on this journey of understanding underglazes together!

What are Underglazes?

Underglazes are a type of ceramic colorant that is applied to pottery or ceramic surfaces before the final glaze firing. They are typically made of clay mixed with ceramic pigments and other additives, resulting in a thick, paint-like consistency. Underglazes are incredibly versatile and can be used to create intricate designs, patterns, and even realistic images on ceramic pieces. They are an essential tool for ceramic artists who want to add vibrant colors and intricate details to their work.

Definition

Underglazes are specifically formulated clay-based colors that are applied to ceramic surfaces before glaze firing. Unlike glazes, which are transparent or translucent, underglazes remain opaque even after firing, allowing for more controlled and vibrant color application. They are typically used in decorative ceramics, but can also be utilized in functional pieces, such as mugs, plates, or vases, to add visual interest. Underglazes can be applied by brushing, spraying, or layering, and they provide a variety of effects, including marbling, crackling, and drips.

Types

There are two main types of underglazes: liquid and dry. Liquid underglazes come in pre-mixed bottles and are ready to use right out of the container. They have a consistency similar to paint and are easy to apply with a brush or sponge. Dry underglazes, on the other hand, come in powdered form and need to be mixed with water before application. They offer more control over color intensity and can be used to create custom colors by mixing different powders together. Both types of underglazes can be found in a wide range of colors, from vibrant primaries to subtle earth tones.

Uses

Underglazes are predominantly used for decorative purposes on ceramic and pottery surfaces. They allow artists to add intricate designs, patterns, and colors to their pieces. Underglazes can be applied to greenware, which is unfired clay or bisqueware, which is clay that has been fired once but has not yet been glazed. They can also be used to accentuate textures or add depth to carved or stamped designs. Once the underglaze has been applied, the piece is typically fired again to a high temperature to vitrify the clay and permanently fix the colors. After firing, a clear glaze can be applied to give the piece a glossy finish and further protect the underglaze.

Choosing Underglazes

When it comes to choosing underglazes for your ceramic projects, there are several factors to consider. From color options to application methods, each decision you make will have an impact on the final result of your piece.

Considerations

Before selecting underglazes, it is essential to consider the intended use and desired outcome of your project. Are you creating functional pieces that will come into contact with food or drink? Or are you making purely decorative items? For functional pieces, it is crucial to choose underglazes that are food safe and will not leach harmful substances. For purely decorative pieces, there are more options available, as you won’t have to worry about food safety. Additionally, think about the firing temperature of your ceramic studio or kiln, as some underglazes are formulated for specific temperature ranges.

Color Options

Underglazes come in a vast array of colors, allowing you to unleash your creativity and experiment with different combinations. When choosing colors, consider the overall aesthetic you want to achieve. Do you prefer bold and vibrant shades, or are you more drawn to soft and pastel tones? Take note of how different colors interact with each other, as some may intensify or mute each other when layered or mixed. It can be helpful to create a color chart or sample tiles to test out different color combinations before applying them to your actual pieces.

Application Methods

Underglazes can be applied using various techniques, each resulting in a different look and feel. One of the most common methods is brushing, where the underglazes are applied with a brush onto the ceramic surface. This method allows for precise control and is ideal for detailed designs or fine lines. Another method is spraying, where the underglazes are diluted and sprayed onto the piece using an airbrush or spray bottle. This technique creates a more uniform and smooth application. Layering underglazes can also create stunning effects by applying multiple colors on top of each other, resulting in depth and dimensionality.

Preparing Your Surface

Preparing the surface of your ceramic pieces is crucial for achieving the best results with underglazes. Proper cleaning, bisque firing, and glaze application are important steps to ensure that the underglazes adhere well and produce vibrant colors.

Cleaning

Before applying underglazes, it is essential to clean the ceramic surfaces thoroughly. Remove any dust, dirt, or oils from the surface by wiping it down with a damp cloth or sponge. Pay close attention to any areas that will be underglazed and make sure they are completely clean. Any residue or contaminants on the surface can interfere with the underglaze’s adhesion and result in a less satisfactory finish.

Bisque Firing

In most cases, underglazes are applied to bisqueware, which is clay that has been fired once but has not yet been glazed. The bisque firing ensures that the clay is hardened and porous enough for the underglaze to adhere properly. Before underglazing, make sure that your bisque-fired pieces are free of any cracks or imperfections. Any flaws in the surface can affect the underglaze’s appearance and make it more prone to peeling or chipping.

Glaze Application

Once your piece has been underglazed and fired, you may choose to apply a clear glaze to enhance the colors and protect the underglaze. Applying a clear glaze will give the piece a glossy finish and add an additional layer of durability. When selecting a clear glaze, ensure that it is compatible with the underglazes you used and the firing temperature of your kiln. Follow the manufacturer’s instructions for applying and firing the glaze to achieve the desired results.

Applying Underglazes

Now that your ceramic pieces are prepped and ready, it’s time to apply the underglazes. Whether you choose to brush, spray, or layer your underglazes, each technique offers a unique way to achieve your desired look.

Brushing

Brushing is a versatile and commonly used technique for applying underglazes. Start by dipping a brush into the underglaze and removing any excess liquid by brushing it against the inside of the container. Apply the underglaze onto your piece in smooth even strokes, working in one direction. If you’re applying multiple layers of underglaze, let each layer dry before applying the next. This will prevent the colors from smearing or blending together. Brushing is ideal for intricate designs, details, or fine lines, as it allows for precise control.

Spraying

Spraying underglazes offers a more uniform and smooth application. This method is ideal for covering large areas or achieving a gradient effect. To spray underglazes, dilute the underglaze powder with water to a consistency that can be easily sprayed. Using an airbrush or spray bottle, apply thin layers of the diluted underglaze onto the surface of your piece. Let each layer dry before applying the next. Spraying creates a different texture and depth compared to brushing and can result in a more seamless and professional finish.

Layering Techniques

Layering underglazes opens up a world of creative possibilities, allowing you to achieve depth, texture, and unique color combinations. Start by applying a base color or colors onto your ceramic surface, either by brushing, spraying, or a combination of both. Once the base layer is dry, apply additional layers of underglaze in a different color or colors. Experiment with different layering techniques, such as sponging on underglaze, splattering, or using resist materials like wax or tape to create interesting patterns and textures. Layering underglazes can give your pieces a sense of depth and complexity that is visually captivating.

Decorative Techniques

In addition to applying underglazes using different methods, there are various decorative techniques you can incorporate to add even more visual interest to your ceramic pieces.

Sgraffito

Sgraffito is a decorative technique that involves scratching or carving through the layers of underglaze to reveal the clay body underneath. To achieve this effect, apply underglaze onto your piece and let it dry. Once dry, use a sharp tool, such as a needle tool or carving tool, to scratch or carve designs, patterns, or even words into the underglaze, revealing the clay body beneath. Sgraffito can create intricate and detailed designs and allows for a high level of control and precision.

Stamping

Stamping is a fun and easy way to add texture and design to your ceramic pieces using underglaze. Start by selecting stamping tools or objects with unique patterns or textures. Dip the stamp into the underglaze and press it onto your ceramic surface. You can create repeating patterns or arrange different stamps to create a custom design. Experiment with different stamp sizes, shapes, and orientations to achieve your desired aesthetic. Stamping adds depth and texture to your underglazed pieces and can create a visually stunning effect.

Stenciling

Stenciling is another popular technique for adding visual interest to underglazed ceramics. Start by choosing a stencil with the pattern or design you want to incorporate. Place the stencil onto your ceramic piece and secure it in place. Using a brush or sponge, apply the underglaze over the stencil, making sure to cover the entire design area. Carefully lift the stencil off the piece, revealing the underglazed design underneath. Stenciling allows for precise and consistent designs and can be used to create intricate patterns or specific images.

Underglaze Effects

Underglazes offer a range of effects that can elevate your ceramic pieces to new levels of visual appeal. From marbling to crackle, these effects can add depth, texture, and interest to your underglazed surfaces.

Marbling

Marbling is a technique that involves blending different colors of underglaze together to create a swirling or marble-like effect. Start by applying your base coat of underglaze onto the ceramic surface. Once the base coat is dry, apply additional colors of underglaze randomly or in a pattern on top of the base coat. Using a tool such as a toothpick or a needle tool, gently drag the tool through the wet underglazes, creating swirls and patterns. Be careful not to overwork the underglazes, as this can blend the colors too much and result in a muddy appearance. The marbling effect adds a sense of movement and excitement to your underglazed pieces.

Crackle

Crackle is a popular effect that creates a network of fine cracks in the underglazed surface, adding an aged or weathered look to your ceramics. There are two main methods to achieve crackle effects. One method involves applying crackle glaze over the underglaze, following the manufacturer’s instructions for application and firing. Another method involves applying a special underglaze crackling medium onto the underglaze and firing it according to the medium’s instructions. Once fired, the medium will create fine cracks in the underglaze, enhancing the overall appearance of your ceramics.

Drips and Runs

Drips and runs can add an element of spontaneity and playfulness to your underglazed pottery. To achieve this effect, apply your underglaze to the ceramic surface and let it start to dry slightly, but not completely. Tilt the piece or hold it upside down, allowing the underglaze to naturally flow and drip down the sides. Experiment with different angles and amounts of underglaze to create various drip and run patterns. This effect can be particularly striking when combined with layered underglazes or contrasting colors. Drips and runs add movement and unpredictability to your underglazed pieces, making them visually dynamic.

Firing Underglazes

Once you have applied the underglazes and have achieved your desired effects, it’s time to fire your ceramic pieces to make the colors permanent and durable. Proper temperature considerations, kiln atmosphere, and firing schedules are crucial for achieving the best results.

Temperature Considerations

Underglazes are formulated for specific firing temperature ranges, so it’s important to consider the temperature of your kiln or ceramic studio. Different underglazes have different temperature tolerances, and firing them outside of their recommended range can result in color distortion, burning, or fading. It is essential to check the firing temperature range specified by the manufacturer and ensure that your kiln is capable of reaching and maintaining the correct temperature. Additionally, be mindful of the temperature differences between your bisque firing and your underglaze firing, as well as any subsequent glaze firing.

Kiln Atmosphere

The atmosphere inside the kiln during firing can also affect the outcome of your underglazes. Most underglazes are designed to be fired in an oxidation atmosphere, where there is ample oxygen during the firing process. However, some underglazes, particularly those containing metallic elements, may require a reduction atmosphere to achieve their desired colors. A reduction atmosphere is achieved by introducing a limited amount of oxygen into the kiln during specific stages of the firing process. It is crucial to follow the manufacturer’s instructions regarding kiln atmosphere to ensure that your underglazes develop their intended colors.

Firing Schedules

Proper firing schedules are essential for achieving the best results with underglazes. A firing schedule refers to the temperature and duration of each phase of the firing process. Underglazes typically require a specific firing schedule to ensure that the colors develop properly and the clay body vitrifies. It is important to consult the manufacturer’s instructions and follow their recommended firing schedule to achieve the desired effects. Additionally, ramping the kiln slowly during specific temperature ranges can help prevent cracking or warping of your underglazed pieces.

Finishing Touches

Once your underglazed pieces have been fired, there are a few finishing touches you can add to further enhance their appearance and durability.

Clear Glaze Application

Applying a clear glaze over your underglazes can enhance the colors, add shine, and provide an additional layer of protection. Select a clear glaze that is compatible with the firing temperature and the underglazes you used. Follow the manufacturer’s instructions for applying the clear glaze and firing it to achieve the desired results. The clear glaze will give your underglazed pieces a glossy finish and protect the colors from fading or scratching over time.

Post-Firing Surface Treatment

After your pieces have been fired and have cooled, you may choose to apply additional surface treatments to further enhance their appearance. These treatments can include sanding, waxing, or buffing the surface to achieve a smoother finish or remove any imperfections. Additionally, you can use specialized ceramic paints or markers to add additional decoration or details to your underglazed pieces. Be mindful of the compatibility of these treatments with the underglazes and glazes you used, as well as their firing temperature requirements.

Decoration

Once the finishing touches have been applied, you can further accentuate your underglazed pieces with additional decoration. This can include adding ceramic decals, luster, or metallic accents to create intricate or eye-catching designs. Furthermore, consider incorporating other materials such as beads, crystals, or metal wire into your ceramic pieces to add dimension and uniqueness. The possibilities for decoration are endless, allowing you to create truly one-of-a-kind works of art.

Troubleshooting Common Issues

While underglazing can be a rewarding and fun process, it is not without its challenges. Here are some common issues you may encounter when working with underglazes and how to troubleshoot them.

Fading or Discoloration

If your underglazes appear faded or have changed color after firing, it may be due to several factors. First, ensure that your underglazes are compatible with the firing temperature of your kiln. Using underglazes that are not designed for your firing temperature can result in color distortion or fading. Additionally, overfiring or underfiring your pieces can also affect the colors. Make sure to follow the recommended firing schedule and accurately monitor the temperature during firing. Finally, check that your underglazes were adequately mixed and applied evenly. Poor mixing or thin application can lead to inconsistent color absorption and result in faded or blotchy underglazes.

Peeling or Chipping

If your underglaze is peeling or chipping off your ceramic piece after firing, it indicates a bonding issue between the underglaze and the clay body. Peeling or chipping can be caused by inadequate cleaning of the ceramic surface before applying the underglaze, improper bisque firing, or compatibility issues between the underglaze and glaze. Ensure that the ceramic surface is completely clean before applying the underglaze, as any residue or oils can prevent proper adhesion. Additionally, make sure that your bisque firing is thorough and complete, allowing the clay body to become hard and porous. Always check the compatibility of your underglazes and glazes, as some combinations may not adhere well together.

Uneven Application

If your underglazes appear uneven or patchy after firing, it is likely due to insufficient or uneven coverage during application. Uneven application can be caused by using too little underglaze or not adequately mixing the underglaze before application. To ensure even coverage, make sure to apply enough underglaze to completely cover the ceramic surface. Additionally, mix your underglazes thoroughly, making sure that any settled pigments or additives are fully incorporated into the mix. Finally, consider applying multiple layers of underglaze, allowing each layer to dry before applying the next. This can help build up the color intensity and ensure a more consistent appearance.

Caring for Underglazed Items

Taking proper care of your underglazed ceramic pieces is essential for maintaining their appearance and durability. By following a few simple guidelines, you can ensure that your underglazed items stay beautiful for years to come.

Cleaning Methods

When cleaning underglazed items, it is best to avoid harsh or abrasive cleaning agents that can potentially damage the surface or remove the underglaze. Instead, use mild soap and warm water to gently clean the surface. Avoid soaking underglazed items for extended periods or using scrub brushes or abrasive sponges that can scratch or dull the surface. If necessary, you can use a soft cloth or sponge to lightly scrub away any stubborn stains. Remember to dry your underglazed items thoroughly after cleaning to prevent water spots or potential damage.

Display and Storage

When displaying or storing underglazed items, it is important to handle them with care to prevent any accidental damage. Avoid placing underglazed pieces in high-traffic areas where they may be prone to accidental bumps or falls. Instead, choose a secure and stable location where they can be enjoyed without risk of damage. When storing underglazed items, make sure they are placed in a safe and secure location, ideally individually wrapped or separated to prevent contact and potential scratching or chipping. Additionally, avoid exposing underglazed items to extreme temperatures or rapid temperature changes, as this can cause stress and potentially damage the ceramic.

Avoiding Damages

To prevent potential damages to your underglazed items, it is important to handle them with care and avoid certain activities that can cause harm. When using underglazed ceramics for serving or dining, avoid using metal utensils that can potentially scratch the surface. Instead, opt for silicone, plastic, or wooden utensils that are less likely to cause damage. It is also essential to avoid exposing underglazed pieces to direct heat sources, such as stovetops or open flames, as this can cause thermal shock and lead to cracking or breakage. Additionally, be mindful of any chemicals or cleaning agents that may come into contact with the underglazed surface, as some can potentially cause discoloration or damage.